Recently services are available for discovering stolen vehicles by utilizing the vehicle position information in GPS (Global Positioning System) for mobile communication devices. In other words, when for example, a request is made to the service center by a vehicle owner whose automobile was stolen, a telephone call is promptly made from the service center to the stolen vehicle instructing that position data be sent. The vehicle swiftly responds to the instruction from the service center and unknown to the thief, sends back position data to the service center.
However, when functions or service of this type are applied not only to tracking stolen vehicles but to general position search services such as for exchange of position data in vehicle-to-vehicle communication or finding the position of terminal users (elderly people, etc.) utilizing PHS, then a stranger may learn the terminal user's position without the knowledge of that terminal user. This creates the potential for invasion of privacy and so on.